Infra red ray generating space heater



Nov. 21, 1967 F.J. SILHAVY E L INFRA RED RAY GENERATING SPACE HEATER 2Sheets-Sheet 1 Filed Aug. 26. 1965 l/VVE/VfdfS F PA/VA J, S/Zl/AV)ROBERT 6/ OEBREY 21 I KIVA Nov. 21, 1967 F. J. SILHAVY ET AL INFRA REDRAY GENERATING SPACE HEATER 2 Sheets-Sheet 2 Filed Aug. 26, 1965 why W n$4 w M 7 W a United States Patent 3,353,583 INFRA RED RAY GENERATLNGSPACE HEATER Frank J. Silhavy and Robert J. Debrey, Oak Park, Ill.,

assignors, by mesne assignments, to Caloric Corporalion, Topton, Pa., acorporation of Pennsylvania Filed Aug. 26, 1965, Ser. No. 482,696 4Claims. (Cl. 158-114) ABSTRACT OF THE DISCLOSURE A gas burning infra redray generator comprising a narrow elongated casing; having an elongatedbottom opening covered by a combustion sustaining screen; a venturi tubedischarging at about the center of the casing; a horizontal perforatedbafile below the venturi and above the screen; a vertical baffleregistering with the lower portion of the venturi tube discharge openingto deflect the gas issuing therefrom toward said horizontal bafile; anda partition dividing the casing above said horizontal bafile intoparallel, longitudinal compartments.

This invention relates to an infra red ray generator of the type Wheregaseous fuel is burned on the surface of a screen to bring it toincandescence which is the optimum temperature for the generation ofinfra red rays.

One object of this invention is to produce an improved radiant burner ofthe type set forth.

A further object is to produce a space heater of a configuration whichpermits a number of heaters to be arranged in any desired pattern so asto provide uniform heat regardless of size or of the configuration ofthe area to be heated.

A still further object of this invention is to provide a space heaterwhich is adapted for indoor and for outdoor use.

A still further object is to produce an improved space heater which issimple, easy to operate, and reliable.

These and other objects are attained by our invention which is set forthin the following specification and in the accompanying drawings inwhich:

FIG. 1 is a view, partly in section and partly in elevation, certainparts being partially broken away to show the internal construction, theview having been taken along line 11 on FIG. 2.

FIG. 2 is a sectional view looking in the direction of line 2-2 on FIG.1.

FIG. 3 is an enlarged sectional view looking in the direction of line 33on FIG. 2.

FIGS. 4, 5 and 6 are schematic examples of the improved radiationpatterns produced by burners embodying the invention.

The gas-burning infra red ray generating heater illustrated consists ofan elongated casing 10, having a relatively narrow bottom opening 12which is covered by combustion sustaining screen assembly 14. Casing 10is preferably formed of sheet metal, and comprises a top wall 16, sidewalls 18, and bottom walls 20, which converge downwardly and the edgesof which define previously mentioned opening 12 which preferably extendsthe entire length of the casing. One end of the casing is closed by endwall 22 and the other by end wall 24 through which passes a venturi tube26. Gas is delivered to the venturi tube by means of a suitable fitting,not shown, which is positioned in, or adjacent the outer, bell-shapedend 27 of the venturi tube.

The screen assembly 14 which overlies opening 12 is formed of two, ormore, screens 23 and 29 which are closely spaced and an outer screen 30which is spaced from screen 29. Screens 28 and 29 are prefer-ably about40 mesh and are clamped in position as shown in FIG. 1, or otherwise.

As best shown in FIG. 1, venturi tube 26 extends into the casing andslopes upwardly in the direction of its inner end. The lower portion ofthe outlet of the venturi tube 26 registers with the inner, upwardlycurved end 32 of an elongated baffle 34, the horizontal portion 26 ofwhich extends substantially the entire length of the venturi tube, FIG.1.

The horizontal portion 36 of the bafiie is provided with openings 38which discharge gas downward toward opening 12. Openings 38 may also beprovided, to the desired extent, in the curved end portion 32 of thebafile. The size, number, spacing and distribution of openings 38 may bevaried with the length and width and depth of the burner. Theapproximate dimensions shown are satisfactory for a burner screen about6' in length and approximately 2 to 3" in cross section. The baffie ispreferably provided with a central partition 40 which divides the gasissuing out of the venturi tube into two streams and helps to supportthe venturi tube, FIG. 1. The outer end 42 of the baffle stops short ofend wall 24 so as to provide an opening 44 for delivering gas quickly topilot burner 46 as soon as the burner is turned on, thereby providingquick ignition without the necessity of waiting until the entire casing10 has filled up. To protect pilot burner 46 from being extinguished byoutside air currents, and from being smothered by the products ofcombustion, it is surrounded by an open, box-like structure 45, FIG. 1.Likewise, outer screen 30 stops short of end wall 24 to allow theinstallation of pilot burner 46 immediately below opening 44 and belowthe adjacent ends of screens 28 and 29, FIG. 1. It will be noted thatthe upper portion of the inner, discharge end of the venturi tube clearsthe baffle 34 and that the gas-air mixture issuing from the venturi tubewill follow the paths indicated by arrows A, B, and C. Laboratory testsconducted with a prototype having an opening 12 of about 3" x 72" showedthat, immediately upon turning the gas on, ignition begins at pilot 46and progresses rapidly and smoothy toward the distal end of the burnerand that extinguishment, due to turning the gas ofi, proceeds in thereverse direction. It will be understood that the fuel is burned overthe outer surface of outer combustion screen 29 and that inner screen 28serves to prevent backfiash. Outer screen 30 is preferably of about #16mesh and serves to re-radiate the energy derived from the combustion offuel. Screen 30 also serves to moderate air currents and makes theburner particularly adapted for outdoor use, and in large, draftyenclosures such as arenas, warehouses, and so on. Screen 30, beingrelatively rigid, also protects fine mesh screens 28 and 29 againstaccidental damage.

Screens 28, 29 and 30 are arcuate in cross section so as to enlargetheir effective surfaces and any, or all, of them, may be undulated asshown in Patent No. 3,122,197, and for the same purpose. The upwardcurvature of the surface of the screens expedites the rem-oval of theproducts of combustion from the screen surfaces to provide for cleanburning of uncontaminated gas with no risk of the flames on the screensurfaces being dimmed or smothered. Communicating with both edges ofscreen 30 are vertical flues which have bottom openings 58 and upperexhaust openings 62. The total exhaust port area is designed largeenough to prevent the accumulation of a layer of burned gases on thesurfaces of screen 30. The convection which develops in fines 60 servesto draw off products of combustion to eliminate any smothering of theburner flames on screen 30 and also prevents any recirculation ofcombustion products into the inlet bell 23 of the venturi tube 26.

Additionally, the burner casing 10 is provided with cooling chambers 2running the entire length of the side walls 18. Cooling chambers 52 aresealed at the bottom and are provided with exhaust openings 54 at thetop. Cooling chambers 52 prevent heat transfer between products ofcombustion in fiues 6t and the interior of casing 10, thus keeping theinterior of the casing at a temperature below the flash point of thefuel mixture in the casing. To further insure rapid removal of theproducts of combustion from screen 3! we provide pendant side wings 56which coact with the adjacent surfaces of screen 30 to form funnelsleading to the openings 53 in the bottoms of fiues 69. Additionally,side wings 56 are constructed of a bright finish which will act as areflector to direct downwardly the infra red emission from the curvedsurfaces of screen 30. Bottom openings 58 of fiues 69 also provide forrelease of atmospheric disturbances directed at the surface of screen 33to further protect the combustion chamber against drafts and gusts ofwind, thus further adapting the burner for outdoor use. But, openings 58must not be large enough to permit movement of air in such quantities orat such rate as to cool screen 30.

The heater of the present invention relies, for its effect, on infra redrays which, like light rays, travel in straight lines. This means that aplanar, square radiating surface will emit rays in a square patternwhich will cover a planar square area, which at a very close range, suchas one foot or so, will be almost equal to the area of the emittingsurface. The same holds true for all planar geometrical configurations.But, as the distances from the emitting to the target surface increases,the area of the pattern on the target surface also increases. Partly toinsure effective heating of the target area and partly because modernceilings are relatively low, overhead installations, in inhabitedquarters, will be from about eight to about ten feet from the targetarea which, for the purposes of this disclosure, will be the floor. Itis to be understood, however, that a heater embodying this invention canbe mounted to irradiate a ceiling, or a vertical wall, or other targetarea or object.

When the target area is such that it can be covered by a single burnerof the same shape, the target area will be acceptabley heated. But,scientifically controlled tests showed that, when the target is of anirregular shape, or when two or more burners are needed to cover thetarget area, acceptable heating can not be achieved by round, or squareplanar heaters because, if the radiation patterns of adjacent heatersoverlap, intermediate hot spots are produced and, if the radiationpatterns are spaced apart, cold spots will result. For example, if a 2 x5' heater is used to heat a 3 x 5 area, it will leave cold marginalareas. If two 2' x 5' heaters are used, their radiation patterns willoverlap and will create a hot spot. In other words, for uniform heating,one must custom-tailor each heater, or one must carry a prohibitivevariety of shapes and sizes in stock.

This difficulty is exemplified in FIG. 4, the area of which is assumedto be 2 x 6. A single burner 2' x 6 will be too heavy and the screensmay warp, and it will not be usable in smaller locations. If it isassumed that heaters of 2' X 2' are practical and if three burners aremounted at a distance of 8' away, their radiation patterns will overlapto produce hot spots at the areas designated by arrows 64. If only twoheaters are used, the gaps between the radiation patterns will producecold spots. If the target area is irregular, or if it is of a valuewhich is not a multiple of the emitting area of burner, the difficultyis multiplied.

The problems posed by way of example, and other similar problems aresolved in the manner diagrammatically shown in FIG. 5, the area of whichis also assumed to be 2' x 6', or the same as that of FIG. 4. Accordingto this invention, four heaters of 3 x 72" are mounted, at a distance of8, so that their radiating patterns meet along lines 66 withimperceptible overlap, or gap between, the radiation patterns emitted byadjacent heaters. It will be noted that the heaters can be arranged toextend in a direction at an angle to lines 66.

The versatility of the burner of this invention is further illustratedin FIG. 6 which shows an area of irregular shape and how it can beadequately covered by the radiation patterns of narrow burners 3 wideand of uniform, or different lengths.

To carry out this invention, the burner can be massproduced in standard2" and 3" witdths and 24", 48", or 72" lengths. Out of this stock ofready-made burners, the desired number, of the desired length and width,are selected and arranged in the desired pattern. Since the width of thetarget area irradiated at any given distance from the emitting surfaceis known, it is'a simple matter to so space the burners that thelongitudinal edges of the irradiation patterns will meet withimperceptible overlap or with imperceptible separation. This is trueonly as long as the width of the burner is small enough so that oneheater will suffice for the narrowest conceivable area to be heated andso the multiple burners can be used to cover multiples of the areareferred to.

In addition to the versatility above noted, the internal structure ofthe heater makes for uniform ignition over a relatively long combustionsurface and permits use of the burner outdoors, or where the ambient airis not as still as it is in ordinary, inhabited enclosures.

It will be noted that when fiues 60 and wings 56 are heated they alsoact as emitters of long wave heat rays which supplement the heatradiated by the screens and, to that extent, raise the efiiciency of theunit. Additionally, side wings 56 can be coated with iron oxide, orground coat porcelain or other emissive material, so as to serve asradiating as well as reflecting surfaces.

The side openings 62 of fiues 60 to prevent rain from reaching thescreens and minimize downdrafts which can occur if openings 62 were inthe top walls of the fiues and which may discourage the rise of theproducts of combustion. This is particularly true when the burner isfirst lit and the upward draft in fiues 60 is weak, downdrafts candiscourage the movement of the products of combustion away from thesurface of screen 30.

Both the diameter of throat 75 and the diameter of outlet 76 of theventuri tube affect operation. Too small a throat limits the entrance ofprimary air with resulting poor combustion. Conversely, too large athroat permits excessive primary air which acts to cool the burnerscreen. An excessively large outlet 76 acts to raise the high gas-airflow under cold conditions and creates ignition problems. The length ofthe portion 77 of the venturi tube also must be in proper relationshipto the overall length of the burner screens. Testing has shown that in a72' long burner the diameter of throat 75 should be about 2"; thediameter of outlet 76 should be about 273"; and the length of portion 77of the venturi tube should be about 12''.

The flow of gas which is needed under hot operating conditions, isexcessive under cold, non-operating conditions and interfered withinitial lighting, or ignition of the burner. Under hot operatingconditions, a stack action develops in the venturi tube which acts inthe reverse direction and interferes with the fiow of gas out of theventuri tube outlet 76. To overcome this difiiculty, the inner end 32 ofthe baffle is arranged to align with a portion of the area of theventuri tube outlet so as to retard the outward flow of gas under coldconditions and so as to neutralize the momentum of gas flow toward theventuri tube outlet 76. In other words, the end 32 of bafile which isjuxtaposed with the venturi outlet serves as a moderator, or modulatorof the gas flow under both hot and cold conditions.

The baffle is of equal importance in its ability to balance the fiow ofgas to all parts of the combustion screen so as to obtain promptignition and so as to insure uniform combustion.

Placing pilot 46 as shown takes it out of the range of flow of theproducts of combustion, which could weaken or extinguish it, and insuresa supply of ambient air sufiicient to keep the pilot lit.

What we claim is:

1. An infra red ray generator comprising an elongated casing having abottom opening substantially coextensive therewith,

an arcuate, combustion sustaining screen covering said opening,

a pair of vertical flues disposed exteriorly of said casing andextending substantially the length of the casing and having bottomopenings adjacent the respective edges of said screen to draw productsof combustion ofi said screen, and

a pair of shields depending from opposite sides of said flues and spacedfrom, and substantially coextensive with, said screen to protect saidscreen from horizontal air currents,

said shields coacting with said flues to accelerate the flow of theproducts of combustion oif said screen and up through said fiues fordischarge through exhaust openings in the upper portion of said flues.

2. An infra red ray generator including:

an elongated casing having a bottom opening substantially coextensivetherewith,

a gas combustion sustaining screen covering said opening,

a venturi type air-gas mixing tube extending longitudinally of saidcasing and said bottom opening having its intake end near one end ofsaid casing and its discharge end near the center of the casing,

a horizontal, perforated bathe disposed between said tube and saidbottom opening and coextensive with the length of said venturi tube andcoextensive with the width of the casing, and

an upwardly curved bafiie coextensive with the width of the casing,carried by the inner end of said horizontal baflle and overlying thelower portion of the discharge end of the venturi tube, to deflect someof the gas flowing through said venturi tube toward the perforations insaid baffle,

the remaining portion of the discharge end of the Venturi tube beingunobstructed to permit the gas to move freely toward the other end ofthe casing.

3. The generator of claim 2 wherein the axis of said venturi tube andthe plane of said horizontal bafile diverge in the direction of saidother end of said casing.

4. The generator of claim 2 and a vertical partition rising from saidhorizontal bafiie toward the underside of the venturi tube and dividingthe portion of the casing above said horizontal baffle into parallellongitudinal compartments.

References Cited UNITED STATES PATENTS 1,977,947 10/ 1934 Luten'oacher.

2,130,086 9/1938 Hart 12692 3,028,909 4/1962 Faure 1581 14 X 3,169,5722/1965 Constance et al. 158-116 3,173,412 3/1965 Wright 12692 3,185,2045/1965 Loeb et a1. 158114 3,219,097 11/1965 Prince et a1. 158-1143,291,187 12/1966 Haensel 158-116 FOREIGN PATENTS 893,101 4/1962 GreatBritain.

FREDERICK L. MATTESON, JR., Primary Examiner. R. A. DUA, AssistantExaminer.

1. AN INFRA RED RAY GENERATOR COMPRISING AN ELONGATED CASING HAVING ABOTTOM OPENING SUBSTANTIALLY COEXTENSIVE THEREWITH, AN ARCUATE,COMBUSTION SUSTAINING SCREEN COVERING SAID OPENING, A PAIR OF VERTICALFLUES DISPOSED EXTERIORLY OF SAID CASING AND EXTENDING SUBSTANTIALLY THELENGTH OF THE CASING AND HAVING BOTTOM OPENINGS ADJACENT THE RESPECTIVEEDGES OF SAID SCREEN TO DRAW PRODUCTS OF COMBUSTION OFF SAID SCREEN, ANDA PAIR OF SHIELDS DEPENDING FROM OPPOSITE SIDES OF SAID FLUES AND SPACEDFROM, AND SUBSTANTIALLY COEXTENSIVE WITH, SAID SCREEN TO PROTECT SAIDSCREEN FROM HORIZONTAL AIR CURRENTS, SAID SHIELDS COACTING WITH SAIDFLUES TO ACCELERATE THE FLOW O THE PRODUCTS OF COMBUSTION OF SAID SCREENAND UP THROUGH SAID FLUES FOR DISCHARGE THROUGH EXHAUST OPENINGS IN THEUPPER PORTION OF SAID FLUES.